Officials revealed a new timeline Monday suggesting the final voice transmission from the cockpit of the missing Malaysian plane may have occurred before any of its communications systems were disabled, adding more uncertainty about who aboard might have been to blame.

The search for the missing Malaysian jet pushed deep into the northern and southern hemispheres Monday as Australia scoured the southern Indian Ocean and Kazakhstan – more than 6,000 miles to the northwest – answered Malaysia’s call for help in the unprecedented hunt.

Vietnam scrambled helicopters Monday to look for what a search jet spotted and believed might have been a life raft from the Malaysia Airlines Boeing 777 that vanished early Saturday morning on a flight from Kuala Lumpur to Beijing with 239 people on board, but the object found floating in the sea was not a boat, leaving the fate of the airliner a mystery.

Interpol knew about stolen passports that two passengers used to board an ill-fated Malaysia Airlines flight bound for China, but no country checked the police agency’s vast database on stolen documents beforehand, it said Sunday. Interpol said it hopes authorities will “learn from the tragedy.”